Support for a workshop on pathogenesis by non-acute retroviruses is requested. Viruses to be considered include murine leukemia virus, avian leukosis virus, feline leukemia virus and murine mammary tumor virus. This will be a focused workshop, covering viral genetics, host genetics, molecular biology, and immunology with regard to the disease process. Recent progress in such areas as oncogene activation, viral determinants in disease, preleukemic states and tumor progression makes the time ripe for an in depth workshop. Projected attendance is 150 people.